Analysis of Two New Arabinosyltransferases Belonging to the Carbohydrate-Active Enzyme (CAZY) Glycosyl Transferase Family1 Provides Insights into Disease Resistance and Sugar Donor Specificity

Louveau, Thomas, Orme, Anastasia, Pfalzgraf, Hans, Stephenson, Michael, Melton, Rachel, Saalbach, Gerhard, Hemmings, Andrew, Leveau, Aymeric, Rejzek, Martin, Vickerstaff, Robert, Langdon, Tim, Field, Rob and Osbourn, Anne (2018) Analysis of Two New Arabinosyltransferases Belonging to the Carbohydrate-Active Enzyme (CAZY) Glycosyl Transferase Family1 Provides Insights into Disease Resistance and Sugar Donor Specificity. Plant Cell, 30 (12). pp. 3038-3057.

[img] PDF (Accepted_Manuscript) - Submitted Version
Restricted to Repository staff only until 14 December 2019.

Download (6MB) | Request a copy

    Abstract

    Glycosylation of small molecules is critical for numerous biological processes in plants, including hormone homeostasis, neutralization of xenobiotics, and synthesis and storage of specialized metabolites. Glycosylation of plant natural products is usually carried out by uridine diphosphate-dependent glycosyltransferases (UGTs). Triterpene glycosides (saponins) are a large family of plant natural products that determine important agronomic traits such as disease resistance and flavor and have numerous pharmaceutical applications. Most characterised plant natural product UGTs are glucosyltransferases, and little is known about enzymes that add other sugars. Here we report the discovery and characterization of AsAAT1 (UGT99D1), which is required for biosynthesis of the antifungal saponin avenacin A-1 in oat. This enzyme adds L-arabinose to the triterpene scaffold at the C-3 position, a modification critical for disease resistance. The only previously reported plant natural product arabinosyltransferase is a flavonoid arabinosyltransferase from Arabidopsis. We show that AsAAT1 has high specificity for UDP-β-L-arabinopyranose, identify two amino acids required for sugar donor specificity, and through targeted mutagenesis convert AsAAT1 into a glucosyltransferase. We further identify a second arabinosyltransferase potentially implicated in the biosynthesis of saponins that determine bitterness in soybean. Our investigations suggest independent evolution of UDP-arabinose sugar donor specificity in arabinosyltransferases in monocots and eudicots.

    Item Type: Article
    Faculty \ School: Faculty of Science > School of Chemistry
    Faculty of Science > School of Biological Sciences
    Depositing User: LivePure Connector
    Date Deposited: 11 Jan 2019 12:30
    Last Modified: 25 Feb 2019 10:30
    URI: https://ueaeprints.uea.ac.uk/id/eprint/69560
    DOI: 10.1105/tpc.18.00641

    Actions (login required)

    View Item